Auckland police are stepping up efforts to find whoever was responsible for an attack on a man in the central city at the weekend that has left him fighting for his life in hospital.

Police say the victim, from Tonga, was seen walking down the middle of Kitchener Street at 3.40am on Saturday, impeding traffic, when a vehicle stopped near him.

"Words were exchanged between the victim and the occupants of this car," said Detective Senior Sergeant Glenn Baldwin of Auckland City Police.

A short time afterwards, the car has driven off at speed and the victim was left lying on the ground, badly assaulted, he said.

Police are reviewing CCTV footage and have spoken to several members of the public who have already come forward with information, but are keen to hear from anyone else who may be able to assist with the investigation, Mr Baldwin said.

"Police need to know how the victim received his injuries and the people in the car on Kitchener Street, can help paint this picture," he said.

"We would like the occupants of the car that to come forward to help Police understand what has occurred."

Anyone with information is being asked to contact Auckland City Police on 09 302 6400 or CrimeStoppers on 0800 555 111.